In the art of turbine design, the need often exists to seal connections between adjacent turbine components, such as turbine blades, in order to separate fluids and to maintain a turbine's efficiency. For instance, it is desirable to separate pressurized air from hot gases in specific locations in a turbine assembly. A common location for separating these gases is at the intersection between adjacent turbine blades proximate to a turbine housing to which the turbine blades are connected.
Typically, baffles, or “key seals,” are implemented, as shown in FIG. 1, to separate cooled air located in interior aspects of a rotor assembly from hot gases located around the turbine blades of a turbine assembly. Most often, the baffles are positioned in recesses, or grooves, located in protrusions in the turbine assembly. The baffles typically are made of hard materials that block a significant portion of the openings between the turbine blades. Most baffles are inflexible and thus are configured to have a small amount of clearance to prevent binding, gauling, or other types of interferences. Thus, as shown by the arrow signifying air flow in FIG. 1, air is capable of leaking around the baffle. Such leakage reduces the efficiency of the turbine and can lead to harmful results.
An alternative baffle has been developed and is shown in U.S. Pat. No. 5,865,600 to Mori et al. The baffle system disclosed in Mori comprises a baffle formed from metallic belt-like members having a cross-section with two ends, whereby each end includes two sealing members that are biased away from each other and wrap circumferentially around the longitudinal axis of a turbine rotor assembly. This configuration gives the baffle a spring-like effect when the sealing members are squeezed together. The cross-section of this belt is oriented generally orthogonal to the axial direction. Thus, Mori discloses a baffle formed from a belt having improved sealing qualities. However, Mori discloses sealing the opening only in the radial direction.
A typical turbine engine usable in power plant applications has numerous openings with diameters between about ⅛ of an inch and {fraction (1/10)} of an inch. Equivalent openings in turbines usable in an aircraft applications are even smaller. Sealing such small openings with relatively inflexible seals, such as the seals disclosed in Mori, is challenging. Furthermore, manufacturing complex seals with dimensions corresponding to such small openings is difficult at least because of the increased difficulty encountered in manufacturing complex aspects of such seals. For instance, creating spot welds, as shown in FIGS. 2 and 3(a) of Mori and identified as element 13, and small slits, as shown in FIG. 3(b) and identified as element 16, in seals having such small dimensions is difficult and costly.
Thus, a need exists for a relatively simple turbine seal capable of securely sealing an opening between turbine components in the radial direction, the axial direction, and the circumferential direction normal to the axial direction.